While the competition to be Oklahoma's next quarterback gets most of the attention, the Sooners need to improve their defense if they want to return to the chase for the national championship.

Last year, with record-setting quarterback Landry Jones closing out his career, Oklahoma had far from a puny offense. The problem was that in certain games and certain key situations, the Sooners' defense could be described as puny.

Finishing 10-3 with a share of the Big 12 championship would be fine for most teams, but it was hardly satisfactory for OU and its fans. The defense averaged allowing 398 yards per game – the most allowed during the Bob Stoops Era.

"We were 10 wins last year, co-champs in the Big 12, and lost to Texas A&M in the Cotton Bowl," Stoops said. "No, we're not pleased about that, but there's improvement to be made, and our guys are excited about making that improvement and hopefully we'll be able to do it."

"I think we're always motivated," Stoops said. "I think when you've been somewhere 15 years, you're not going to win the championship every year, but I think we've done a pretty consistent job."

Last season's accomplishments were dulled by the defensive's performance. In four of OU's last five games, it allowed 34 or more points and gave up 41 or more in three games. The final memory of last season was a 41-13 loss to Texas A&M and Heisman Trophy winner Johnny Manziel, who had 516 yards of total offense (287 passing, 229 rushing).

For the season, Oklahoma allowed nearly 400 yards and 25.5 points per game. They were next-to-last in the Big 12 in rushing defense, allowing 192.2 yards and 5.2 yards per attempt.

"If you can't stop the run, it becomes very difficult to play good defense, and our inability to consistently stop the run down the stretch was frustrating," OU defensive coordinator Mike Stoops said. "Winning is the most important thing to us, playing good enough defense to win. Our expectations will be to play great defense."

When Mike Stoops was OU's defensive coordinator from 2000-2003, the Sooners won a national championship and averaged 34 takeaways per season. Last year OU forced just 16 turnovers, had 25 sacks and 55 tackles for loss.

"That just comes with being aggressive. When you're aggressive and out there flying around trying to make a play then that's when they're going to start happening," senior cornerback Aaron Colvin said. "When you're zoned into your keys, when you're tuned into what coach is trying to teach you during preparation week, then that's when you're going to make plays.

"The more prepared you are, the more plays you make. We're going to be more consistent this year as far as preparing and we're going to be a lot more aggressive and physical."

Three Key Questions1. Who will play quarterback and how well will he play?For the first time since 2007, the Sooners spent the offseason wondering who would be their quarterback. Junior Blake Bell, famous for his short yardage heroics in the "Bell Dozer" package, has attempted just 20 passes. Redshirt freshman Trevor Knight has displayed ability and poise during preseason practices.

2. Will the defense improve?Coordinator Mike Stoops admits last year's defensive game plans were too basic and that opposing teams were able to out-scheme the Sooners. To combat the Big 12's up-tempo and spread offenses, Stoops will use more five-man secondary groups and will try to get more speed on the field. The defensive line needs to be more dynamic at pressuring the quarterback and a number of players on that unit are untested.

3. Who'll emerge as the top receiving threats?The Sooners must replace the top two receivers from last season; Kenny Stills and Justin Brown combined for 155 receptions. Senior Jalen Saunders had 62 catches last season and figures to be the go-to receiver for whoever plays quarterback. Sophomores Trey Metoyer and Sterling Shepard are both talented and will need to be consistently productive.

Information, PleaseLeft tackle on Oklahoma's offensive line has become a position that results in a pro career. Last year, Lane Johnson played well enough to become a No. 1 pick. He was preceded by Trent Williams, Donald Stephenson, Phil Loadholt and Jammal Brown. Junior Tyrus Thompson (6-5, 320 pounds) figures to replace Johnson this season. … For the first time since 2000, Oklahoma is outside the top 10 in the preseason pools. The Sooners are No. 16 in the USA Today/coaches poll and No. 16 in the Associated Press rankings. OU won the national championship in 2000. … Bob Stoops is nine victories short of becoming the winningest coach in school history. Going into his 15th season, Stoops has 149 wins; Barry Switzer holds the OU record with 157 victories.

Numbers To NoteOver the last four seasons, Oklahoma has thrown it more than it has run it. In 2009 and 2010, the Sooners attempted a pass on 51 percent of their plays. In 2011, that went up to 56 percent and last year it was 57 percent – the highest since Bob Stoops became coach in 1999. … In Stoops' 13 seasons, Oklahoma has never lost consecutive regulars-season games. … The Sooners have 34 seasons with 10 or more victories – no program has more. … Junior kicker Michael Hunnicutt has made 38 of 45 field goal attempts and is 111 of 114 on extra point attempts in two seasons.